A Porphyrin-Based\nMOF Thin Film with Oriented Nanosheet\nArrays for Optimizing a Nonlinear Optical Response

Developing two-dimensional (2D) hybrid nanosheet arrays\nintegrating\ninorganic and organic components is highly significant for third-order\nnonlinear optical (NLO) applications. Herein, an oriented 2D porphyrin-based\nMOF (ZnTPyP(Co)) thin film composed of vertically stacked ultrathin\nnanosheets was fabricated via the liquid-phase epitaxial (LPE) layer-by-layer\n(LBL) method. The prepared ZnTPyP(Co) thin film exhibits an outstanding\nthird-order NLO response with a high third-order nonlinear susceptibility\nof ∼2.63 × 10<sup>–7</sup> esu, which is ascribed\nto the hybrid nanosheet array structure. Additionally, experimental\nZ-scan measurement and theoretical calculations also demonstrate that\nthe substitution of Co metal ions in the porphyrinic core can increase\nthe level of delocalization of the porphyrinic group and contribute\nto the material’s enhanced NLO properties. These findings not\nonly provide new film candidates for NLO application but also highlight\nthe potential of 2D MOF nanosheets in advanced optical devices.